Help with VC filters

Discussion in 'B&W: Film, Paper, Chemistry' started by NDKodak, May 17, 2013.

  1. NDKodak

    NDKodak Member

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    A few questions about using VC paper and filters.
    Which is effected more by the filters the shadow areas or the highlight areas?
    It has been a number of years since I used a darkroom and I am trying to recall he best way to use the VC filters. I thought it was start with the #2 yellow then figure out the enlarger time based on how you liked your shadow area (or was it highlight area I can not remember which it was), then once enlarger time was set you used the filters to get your highlight areas to print how liked.
    Does this sound correct of am I mistaken?
     
  2. MattKing

    MattKing Subscriber

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    Well ......

    Most of the filter systems are designed to be speed matched on a middle grey.

    Generally speaking, I prefer to start by testing toward an exposure time and contrast filter that gives me the results I need for a middle grey. Then I add burns and dodges for the shadows and highlights. Typically, I will adjust the contrast filtration separately for both the shadows and the highlights.

    The higher contrast filters affect the dark parts of the image the most, so if you don't want to use different filtration for different parts of the scene, I would suggest adjusting your exposure (with a #2 filter) until you are pleased with a light gray tone, and then adjust your filtration until the shadows are sufficiently black.
     
  3. Maris

    Maris Member

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    The key thing with multigrade paper is knowing what changes and what stays the same when contrast filters are changed.

    Use test strips to discover the exposure that gives Print Value VIII from the parts of the negative that have Density VIII corresponding to exposure Zone VIII. This stays the same when you change contrast grades. In a nutshell, get the high values right with exposure and jog the dark values up or down by changing contrast filters.

    If you try to work with a mid-tone you will see it go darker if you go up one contrast grade. Then if you make that mid-tone lighter again by reducing exposure the top of your highlights "blow out" to paper base white and the photograph fails. It's the detail bearing highlights, Zone VIII in zone-speak, that you have to nail and then swing the dark tones around that fixed point. Local controls such as burning and dodging play a part too.
    Multigrade emulsion tonal response is approximately linear from one grade to the next for the dark tones, The light tones don't move. Multigrade emulsion speed (light sensitivity) is usually rigged by the manufacturer of the paper and the filters to be constant up to grade 3.5 and half that beyond 3.5.

    Unmentioned are a hundred grace-notes and nuances that turn bothering paper in a darkroom into a nice art.
     
  4. DREW WILEY

    DREW WILEY Member

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    Yellow or green filtration will burn in highlight details. Magenta or blue filters will expose the high-contrast layer, so affect mainly shadows.
    The stronger the density of the filter with respect to its color, the stronger the effect will be in that particular direction. The less intense the
    color, the more white light it will pass, and thus affect both layers to the emulsion. (This explanation is a bit oversimplified, but it works from
    a practical standpoint). Beyond this basic set of facts, there are many variables.
     
  5. Mainecoonmaniac

    Mainecoonmaniac Subscriber

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    In general, try to print for your highlights then use the filter grades to adjust the shadows. However, these are just generalizations. If your highlights have detail, but your shadows are weak, bump up your filter number. Consider the look of your image as a whole. Don't get too stuck on highlights or shadows. You will learn about filter grades as you print more.
     
  6. michael_r

    michael_r Subscriber

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    There are different ways of doing it. But a fairly standard method is to start out with something around a #2 or a little lower, use a key detailed highlight or upper mid tone value to establish a starting point for your exposure time and then adjust the filter number to get the dark tones where you want them and/or control the total and local contrast (a higher filter number will increase contrast, a lower filter number will decrease contrast). Speed matching of filters is typically at a light midtone, so once you establish your exposure based on detailed highlights you might still need to adjust that exposure time a little as you change filters, in order to keep the highlights where they were.

    This Ilford publication is a good resource:

    http://www.ilfordphoto.com/Webfiles/2010628932591755.pdf
     
  7. NDKodak

    NDKodak Member

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    Thank you everyone for taking the time out to respond to my questions about using VC filters, it was very much appreciated.